Water, oxygen, and unwanted organic residues can be detrimental to semiconductor device operation or useful lifetime. This is specifically true in organic semiconductor-based devices such as organic light emitting devices or photoresponsive devices where water or oxygen can lead to electrode degradation or degradation of the active light emitting, absorbing, or charge transporting materials that are necessary for proper functioning of the device. In general, an electronic device includes the placement of conductive electrodes or isolated features along with dielectric or semiconducting materials. In the cases of typical organic light emitting devices or photoresponsive devices, active semiconducting and/or emissive, absorptive or charge transport materials are sandwiched between conductive electrodes that provide charge carrier injection or charge carrier extraction into or out of the active regions within the device. The electron injecting electrode is referred to as the cathode. In some organic light emitting devices, such as the doped organic light emitting device structures produced in U.S. Pat. No. 6,605,483, the device stack is formed with an underlying, semi-transparent, hole-injecting anode electrode arranged on a substrate, that might have water or oxygen barrier properties, followed by a layer of active material, and with a cathode electrode placed on top of and in direct contact with the active material. In some instances, this device is then encapsulated by deposition of thin barrier films on top of the cathode, or by sealing the device through the use of a barrier film and/or adhesive that is fixed to the cathode side of the device, thereby encapsulating the device and restricting the ingress of O2 or H2O through the anode-side barrier substrate film and the topside encapsulation films. This process can also trap O2, CO2, H2, H2O, or other unwanted species that are present from the starting materials or introduced during the fabrication process into the interior of the device, where they could interact with the electrodes or active materials in the device.
Typical conductive paste components, in addition to the conductive materials themselves which might be metal flakes, particles, nanoparticles, nanotubes, organic conductors, or polymeric conductors, can be sources of residual water or impurities. For example, a conductive paste formulation might also include polymer or organic binder materials, such as polyesters, polyurethanes, conducting polymers, polythiophenes, polyanilines, or epoxies, that can contain residual water or other impurities, or it might attract, absorb, or produce residual unwanted impurities once printed onto the device. Other materials that could be sources of unwanted impurities in the ink include surfactants and additives, including ionic, nonionic, and amphiphilic agents, and impurities on particle surfaces or dispersed in the nonmetallic component of the ink or paste.